The present invention relates to an engine chain cover, and more particularly to an engine chain cover adapted to additionally function as a passage for blow-by gas generated from an engine crankcase.
In general, a certain amount of blow-by gas leaks into the crankcase from the combustion chamber while an engine is running, whereby engine oil is thinned down or changed in quality by influences such as heat, moisture in the blow-by gas, thereby generating sludge.
In order to prevent this phenomenon, a ventilation device known as breather is mounted at a crankcase to discharge the blow-by gas into the atmosphere. The blow-by gas, however, contains a large amount of hydrocarbons or carbureted hydrogen to become a source of air pollution such that a positive crankcase ventilation device is used to forcibly introduce the blow-by gas into the suction system of the engine and again send same to the combustion chamber for combustion.
In other words, blow-by gas generated from a cylinder block is induced to flow into the head cover of the engine through passages provided in the cylinder head, where oil is separated from blow-by gas to be re-cycled to an oil pan. The blow-by gas removed of oil is burnt again in the combustion chamber of the engine. However, past attempts to address such problems have generally resulted in increased manufacturing cost of the cylinder head and difficulty in processing.
The present invention provides an engine chain cover capable of inducing the blow-by gas collected at the crankcase to flow into an upper portion of the engine. In accordance with an embodiment of the present invention, there is provided an engine chain cover formed with a passage for inducing the blow-by gas collected at a crankcase into an interior portion of a head cover mounted above a cylinder head. The passage comprises a groove vertically formed at one side of the chain cover, and a plate for blocking an open side of the groove to form the passage.
In an alternative preferred embodiment, the cover comprises an outer cover member having a raised portion to define a grove therein. The raised portion is configured and dimensioned such that when mounted on the engine the groove extends from a position proximate the crankcase to a position proximate the cylinder head. An inner plate covers the groove to define a blow-by gas passage therethrough. The plate is configured and dimensioned to define an inlet proximate the crankcase and an outlet proximate the cylinder head. Also, a seal is provided at the outlet adapted to seal against the cylinder head. Ribs may also be provided for stiffening the plate.
In a further preferred embodiment, the cover thus described is provided in combination with an engine. In this embodiment, a head cover is mounted on the cylinder head and defining a space therein. A hole is defined by the cylinder head and provides communication between the head cover space and the chain cover passage. The cover seals around the hole such that blow-by gas may pass from the crankcase through the inlet to the head cover space via the chain cover passage and the hole. Preferably the cylinder head defines a single hole communicating with the chain cover, although more may be provided as designated by a person skilled in the art.